Multiple-roller calenders are known and are used for the production of plastics material films. It is very important for the penultimate roller traversed by the plastics material to be mounted in the calender support column in a clearance-free manner. More especially, it must be ensured that counter-bending devices normally used in such calenders, and also the separating forces produced by the material being calendered, have as little effect as possible on the bending of the penultimate roller. For accurate calendering, the penultimate roller must be retained accurately in its desired position in the calender support columns.
A calender of this general type is disclosed in U.S. Pat. No. 3,347,157. Such calender includes a roller bearing arrangement comprising a friction bearing formed from two half shells, one portion of which can be acted upon by hydraulically-actuated means in order to make the bearing itself clearance-free.
The above-described arrangement is not entirely satisfactory because there are numerous disadvantages associated therewith. The greatest disadvantage resides in the fact that it is impossible to achieve uniform absorption of forces in the split bearing ring.
If relatively strong forces are applied to the half-shells in order to compensate for play in the bearing, a considerable braking effect is exerted upon the roller journals and hence upon the inner bearing ring. Consequently, these bearing components become subject to considerable wear phenomena. As the wear sustained by the curved bearing component increases, it loses its original shape, with the result that the forces are non-uniformly transmitted. This, in turn, leads to the wear phenomena being further increased.
In addition, the provision of the hydraulically-actuated cylinders is disadvantageous in itself. Such hydraulically-actuated cylinders occupy a relatively large volume and hinder the operator of the calendering device. In order to overcome this problem, suitable covers therefor must be provided which occupy additional space and are expensive.